Tennis racket or the like



R. M. GLENN TENNIS RACKET OR THE LIKE Filed. June 15. 1922 n/Ve n or.'

' is also met in producinfr Patented Mar, ll, i924.

ontarien stares entrainer ovaries.

:ROLAND M. GLENN, 0l?? NEW YORK, N. Y., A SSGNOR T0 AMERICAN' MAGNESIUM CORPQRATON, 0l? NIAGARA FALLS, NEW YORK, AACORPORATION OF NEW YORK.

TEN'NIS G1R. THE LiKE.

Application filed June .15,

To all whom i may concern:

Be it known thatpl, ROLAND M. GLENN, citizen ci the United States, residing at New lif'orlr, in the county of New York and State of New York, have invented certain new and useful improvements in Tennis Rackets or the lille, ci which the tollowing is a specification.

My invention relates to metal game-racket iframes, and one of, the objects oi. the invention is to provide such a trame, particularly for tennis rac-lists, which can be made within the established range of weights :tor such devices, which will have the necessary stiffness or rigidity, the required elasticity, susceptibiiity to easy fabrication and good wearing qualities.

lin adapting the invention to tennis racket frames, certain established requirements must be met. Such frames are now made almost entirely ot wood, the preferred species for this purpose being ash. rlhe continued use oi' wood, particularly ash, has developed certain standards, including a range of weights, viz, from 12 to 16 ounces, within which such rackets must fall. The practice of using ash has also determined the size of the frame members, as well as their stiness and elasticity. lVood frames are open to objections, the principal one 'of which is the tendency to warp, necessitating the keeping of the racket clamped in a press when not in use. Another serious objection is the tendency of wood frames to split. Difficulty good ash frames within the required standard of weights.

ln the attempt toovercome the inherent objections to wood frames, various types otfy metal frames have been experimented with. With this end in view, such :trames have been made out of iron, aluminum and light rigidity.

1n ordinary play, a tennis racket is subjected to a wide and variable range of forces,

1922. Serial No. 583,373.

the effect of which cannot be reasonably foretold. So variable are these factors that it has been found that it is impossible to predict in advance of trying whether a niaterial otherwise having the necessary proporties will stand up under the strains to which the racket/is subjected.

ln Stringing the racket and in order that the desired tension may be retained in they strings, the frame cannot be too rigid. @n the other hand, the trame must not be too iiexible, for it would then be unsuitable for play, as Well as not permitting desirable tension of the strings.

l have discovered that when the frame is made out of a suitable section of metallic magnesium or a high magnesium alloy, that all the undesirable properties of an ash frame are eliminated and all the necessary and desirable properties of a wood frame are retained, and in addition an improvement is effected in the-desirable properties. So far as I am now aware, no other metal has as yet been discovered that has the combination ot properties necessary for its use in this relationship.

Referring to the drawings for a more complete disclosure of the invention:

Figure 1 is a plan view showing a tennis racket embodying the invention;

vFigure 2 is a side view;

Figure 3 is a section on the line A-A of Figure 1, and

Figure 4 is a section on the line B--B of Figure 1. I'

ln the tennis racket shown, the bow 2 is formed of an extruded tube of magnesium, or highly magnesium alloy, which is bent into anoval shape with its two ends being extended and brought together to provide handle portions 3. ln order to strengthen the frame and to give the handle the proper shape, wooden strips lare provided along the sides, a iller strip 5 is provided between the metal handle portions, and a filler block 6 is insertedat the throat of the racket. In Stringing the racket, holes 7 are drilled transversely of and through the tube, vvthe holes being slightly rounded oi to yavoid cutting the strings.

It will be apprehended that the invention is susceptible of a number of embodiments and that the details of construction may be changed and the relative position of certain or the'parts may be altered; the embodiment shown and described therefore is to be` considered as indicative only of the principles of the invention. This embodiment, however, has been found to be practical in construction and operation and edi cient in use."

As has already been pointed out, the metal which is used may be magnesium, or it may be a high ma nesium alloy, as 94% ma nesium and A6% a uminum, or any other hig magnesium alloy, provided its specific gravity does not greatly exceed the specific gravity of ma nesium. The tube is pro duced by extrucgling the metal through a die of the desired cross section, and in the embodiment illustrated, the external shape and dimensions of the tube conform to those of the conventional wooden ash frame. In making the frame, a straight extruded piece of tublng' may be bent either hot or cold around a form the racket. L

Although I have shown an extruded piece of tubing for making the frame out of'magnesium metal, it is obvious that other sh-apes might be employed, provided certain principles are adhered to. Hollow magnesium tubmg or equivalent sections have advantages over solid wood frames of the same external dimensions and same weight, when subjected Yto beam stresses, such as are set up in a tennis racket. Assuming ash wood to have an allowable tensile strength three-tenths that of magnesium, the beam strength of la hollow magnesium beam of the same weight and external -dimensions is about 1.8 times that of the wooden beam. Similarly, a hollow magnesium tube of the dimensions considered has nearly 3% times the beam strength of a solid magnesium rod ofthe same weight.

Theoretically it is possible to make a hollow section of any but the soft metals which will have the beam strength of a solid Wood section of the same` weight per unit of length, simply by increasing the size of the hollow sectionv and at the same time decreasing its wall thickness. In practice, however, an increase in size of section over that of the wood frame is undesirable from a playing standpoint. The allowable rnini-v mum thickness of wall is determined not only by the necessary rigidity and elasticity the frame as a whole must have to meet the requirements for proper Stringing and the varying conditions of play, but also bythe necessary strength the walls themselves must have to withstand local strains due to stringmg, accidents or other causes. It is in this lrespect that l have discovered that magneslum has the necessary combination of physical pro erties not possessed by any of the metalsw ich have heretoforebeen tried for this purpose.

to secure the desired shape of to these holes can be well rounded off and thereby decrease the risk of breaking the strings at these' points. The increased thickness of metal possible adjacent to the holes strengthens the section suiiiciently to prevent local distortion under the tension of the racket strlngs.

The metal usually has an ultimate tensile strength of about 35-45000 lbs. per square inch. This property in conjunction with lightness permits the use of a section, whlch `when lsubject to the stresses set up in a racket, is stronger than the best solid ash, having the same outside dimensions and the same weight per unit of length.

Magnesium and magnesium alloys are articularly adapted to lie formed into shape y extrusion, which thereby permits the production of a hollow tube without any longitudinal joints, which might develop `lines of weakness. .Howeven sections either with or without longitudinal'joints can be used and still have the advantage that the metal permits a good sectional distribution for strength.

The metal .can be readily bent to the proper forms while either hot or cold. The line machining qualities of magnesium facilitate the necessary drilling of racket frames `and such other machlne work as may be necessary. .f

While I have described the production of a hollow section by extruding the metal, it will be. understood that the desired cross section of metal may be secured by any `of the other Well known metal shaping operations to which magnesium is susceptible. By the term magnesium in the claims,` I comprehend not only the elementary metal but also such magnesium base alloys as lend themselves to similar fabrication treatments.

Although the invention has its greatest 1. A. tennis racket or like frame made of a sectionlof magnesium having the requisite beam strength and rigidity as compared to a hollow tube ofcmagnesium having the 10 the conventional ash frame of the same requisite beam strength and rigidity as com- Weight. pared to the, conventional ash frame of the 2. A tennis racket or like frame made of same weight and external dimensions and 5 a hollow tube of magnesium having the having a Wall thickness of section which requisite beam strength and rigidity as com'- will offer the requisite resistance to defor- 15 l pared to the conventional ash frame of the mation from Stringing or external blows. same Weight and external dimensions. In testimony whereof I aix my signature. 3. A tennis racket or like frame made of ROLAND M. GLENN. 

